We did this to improve our capabilities and lower our costs.
Yahoo's web service level was reasonable, but their customer service was poor and their prices were too high. We're saving more than half the cost of running our site by switching. Also their tools are a bit better.
Click the link below to find out about their offerings or Contact me via email if you'd like to why we switched in more detail.
Note - Our BLOG remains with Google's Blogger.com. We're very happy with this service.
see: http://raptordance.com/Hosting.html for more info